The mammalian retina is one of the richest sources of zinc (per weight of tissue) in the body. The trace metal probably subserves a variety of functions, one being an essential component for the activity of alcohol dehydrogenase. Other zinc-dependent reactions and processes have not been investigated systematically. We observed that a chelator of divalent cations, when administered systemically, causes deposition of an electron-opaque material in the retina. The inclusion bodies are distinct from normal subcellular organelles such as lysosomes. Doses of chelator which affect the retina also cause significant reductions in serum zinc, and marginal reductions in blood glucose. The consequences of acute metal chelation on visual function are currently under investigation.